Finishing method for large-diameter high-precision thin-wall nickel-copper alloy piston ring forgings

Abstract

The application relates to a finish machining method of a forged piece, in particular to a finish machining method of a large-diameter high-precision thin-wall nickel-copper alloy piston ring forged piece, which uses a tool flange, a plurality of uniformly distributed threaded holes are arranged in the inner and outer two circles of the upper end face of the tool flange; a numerical control vertical lathe is matched to realize finish machining of the large-diameter high-precision thin-wall piston ring forged piece, different clamping modes are realized only by different tool flange pressing plates, so that finish turning is respectively performed on the two end faces, the inner hole face and the outer circular face of the piston ring, the clamping pressure is controllable, the influence on the surface quality of the piston ring is reduced to the maximum extent, the application has the advantages of simple process, low manufacturing cost, high machining efficiency, short cycle, good precision, simple machining tool and good flexible applicability.

Description

TECHNICAL FIELD

[0001] The application relates to a machining method of a forged piece, in particular to a finish machining method of a large-diameter high-precision thin-wall piston ring forged piece. BACKGROUND

[0002] The piston ring is a reciprocating component, and the machining precision requirement is relatively high; shape and size tolerance will affect the sealing performance and cause the piston ring to be stuck in motion, affect the use function of the piston ring, and cause the device to fail. For a large-diameter high-precision thin-wall nickel-copper alloy piston ring, the nickel-copper alloy material is prone to heat generation during machining due to rapid temperature rise, and is prone to deformation during finish machining, resulting in shape and size tolerance, and even piston ring scrap in severe cases, thereby prolonging the production cycle and increasing the manufacturing cost.

[0003] CN108526937 A machining piston ring with special fixture and turning method for machining piston ring, relates to a fixture and a turning method, which comprises a clamp body, a gland, a plurality of pressing plates and a plurality of supporting blocks corresponding to the number of pressing plates; the middle part of the clamp body is provided with a positioning groove, the gland is installed in the positioning groove for pressing the piston ring, the outer side of the positioning groove is provided with an annular protrusion for positioning the gland and supporting the piston ring, and a plurality of supporting blocks are uniformly distributed on the upper end face of the clamp body, and each supporting block is provided with a pressing plate for pressing the piston ring. The turning method for machining the piston ring comprises the following steps: step one, turning the inner hole; step two, turning the outer circle. The application ensures that the piston ring completes the inner hole and outer circle turning machining in the same station, and improves the machining quality of the piston ring component. The technical scheme aims to solve the coaxial problem during machining of the inner circle and the outer circle. However, the following problems still exist: 1) multiple special tools are required, i.e. in addition to the clamp body, corresponding special-shaped glands, pressing plates and supporting blocks are also required, and the flexibility is poor, which cannot adapt to piston rings of different sizes; 2) only the inner circle and the outer circle of the piston ring can be machined, and the two end faces cannot be finished, and the machining efficiency is not good. SUMMARY

[0004] The application is to solve the above technical problems, and provides a finish machining method of a large-diameter high-precision thin-wall piston ring forged piece, which is simple in process, low in manufacturing cost, high in machining efficiency, good in precision, short in cycle, simple in machining tool and good in flexibility and applicability.

[0005] The finish machining method uses a tool flange, and a plurality of uniformly distributed threaded holes are arranged in the inner and outer circles of the upper end face of the tool flange;

[0006] The finish machining method comprises the following steps:

[0007] I. The tool flange is placed on the numerical control vertical lathe chuck, the top surface is upward, the piston ring is placed on the end surface of the tool flange, and the piston ring is placed on the tool flange outside the piston ring. The multiple pressing blocks are evenly placed on the tool flange outside the piston ring, the end surface of the pressing block is in contact with the outer circular surface of the piston ring, the waist-shaped hole on the pressing block is aligned with the outer circle threaded hole of the tool flange, the inner hole surface of the piston ring is used as a reference, the locking bolt is used to pass through the waist-shaped hole on the pressing block and the tool flange, and the piston ring is fixed to the tool flange. The piston ring is precisely machined on either end surface, leaving a single-sided 0.4-0.5mm finishing allowance, and the end surface is detected by using a dial gauge to ensure that the end surface runout is less than or equal to 0.02mm.

[0008] II. The piston ring is turned over, the other end surface is upward, the piston ring is placed on the tool flange, and the other end surface is machined by repeating step I. The other end surface is machined, leaving a single-sided 0.4-0.5mm finishing allowance, and the end surface is detected by using a dial gauge to ensure that the end surface runout is less than or equal to 0.02mm.

[0009] III. The inner hole surface of the piston ring is precisely machined, leaving a single-sided 0.4-0.5mm allowance, and the inner hole surface of the piston ring is ensured to have a cylindricality of less than or equal to 0.03mm. The actual measured size D1 of the inner hole is recorded.

[0010] IV. The piston ring is removed from the tool flange, the end surface of the tool flange is machined, the outer circle size D2 of the boss is machined, the height is 5-6mm, the outer circle of the boss is machined according to the actual measured size D1 of the inner hole of the piston ring, and the interference amount is ensured to be 0.02-0.03mm. The piston ring is fixed and installed on the tool flange, the inner hole surface of the piston ring is matched with the outer circle of the boss of the tool flange, multiple pressing blocks are evenly placed, the end surface of the pressing block is in contact with the inner circular surface of the piston ring, the waist-shaped hole is aligned with the inner circle threaded hole of the tool flange, the locking bolt is used to pass through the waist-shaped hole on the pressing block and the tool flange, and the piston ring is fixed to the tool flange. The outer circular surface and the sealing groove of the piston ring are precisely machined, the outer circular surface is left with a double-sided 0.1mm polishing allowance, and the outer circular surface of the piston ring is polished to the design requirement.

[0011] V. The piston ring is removed, the outer circle of the boss of the tool flange is machined, and the diameter D3 of the machined boss outer circle is ensured to be less than or equal to 30mm smaller than the inner hole surface of the piston ring. The piston ring is placed on the tool flange, the outer circle is aligned, the outer circle runout is ensured to be less than or equal to 0.03mm, steps I to III are repeated, and any end surface, the other end surface and the inner hole surface of the piston ring are sequentially precisely machined to the design requirement.

[0012] In step II, after the piston ring is turned over, the end surface of the piston ring is in contact with the upper end surface of the tool flange, and the end surface of the piston ring is ground by manually rotating the piston ring.

[0013] In the fourth step, after the piston ring is fixedly installed on the tool flange, the upper end surface of the piston ring is gently knocked by a rubber hammer, and the gap between the lower end surface of the piston ring and the upper end surface of the tool flange is checked by using a feeler gauge, so that the gap is ensured to be 0.03 mm.

[0014] In the fifth step, after the piston ring is taken off from the tool flange, the piston ring is first placed horizontally and naturally aged for more than or equal to 5 days.

[0015] The upper end surface of the tool flange is uniformly provided with a plurality of grooves in the circumferential direction, and the front end of the groove protrudes beyond the position of the corresponding upper end surface of the tool flange on the outer circular surface of the piston ring.

[0016] The thickness of the piston ring is measured by using a 25-50 mm range outer diameter micrometer gauge through the groove of the tool flange.

[0017] Beneficial effects:

[0018] 1) The present application uses only one tool flange pressing plate as a clamp, cooperates with a numerical control vertical lathe to realize the finish machining of a large-diameter high-precision thin-walled piston ring forging, realizes different clamping modes through different tool flange pressing plates, and respectively finishes machining the two end surfaces, the inner hole surface and the outer circular surface of the piston ring, the clamping pressure is controllable, the influence on the surface quality of the piston ring is minimized, the clamping mode is simple and effective, and the working efficiency can be greatly improved; the waist-shaped hole is arranged on the pressing block, the pressing force can be flexibly controlled, clamping deformation is avoided, and different sizes of piston rings are adapted.

[0019] 2) In order to further improve the precision, the other machined surfaces of the piston ring except the outer circular surface are machined twice, the first time machining leaves a finish machining allowance, and the precision of the second time machining is ensured; each time machining, the two end surfaces of the piston ring are machined first, and then the inner hole surface is machined, so that the deformation of the piston ring in the machining process can be effectively reduced, the machining stress is fully released, and the size and shape tolerance precision of the piston ring is ensured.

[0020] 3) When machining the outer circular surface, the boss is machined on the upper end surface of the tool flange, so that the piston ring can be sleeved on the outer circle of the boss, the inner hole surface is in interference fit with the outer circle of the boss of the tool flange, the coaxiality of the inner hole surface and the outer circular surface of the piston ring is ensured, and the contact between the end surfaces of the plurality of pressing blocks and the inner circular surface of the piston ring is ensured, so that the deformation problem does not occur when the outer circular surface is finish machined, and the outer circular surface can be machined to the design size at one time under the above premise.

[0021] 4) After the outer circular surface is machined, the piston ring is placed horizontally and naturally aged for more than or equal to 5 days to eliminate stress, and then the second time machining is performed, so that the two end surfaces and the inner hole surface of the piston ring are machined to the design size.

[0022] 5) On the upper end face of the tool flange, a plurality of grooves are evenly opened in the circumferential direction, and each time the end face of the piston ring is precisely machined, the thickness of the piston ring in different directions can be conveniently measured through the plurality of groove positions by using a 25-50mm range outer diameter micrometer, so as to further improve the machining precision.

[0023] 6) The process is simple, the manufacturing cost is low, the machining efficiency is high, the cycle is short, the machining tool is simple, the flexibility and applicability are good, and the process is particularly suitable for the finish machining of large-diameter high-precision thin-wall nickel-copper alloy piston ring forgings. The machining precision is high, and the following strict design requirements can be met: the outer diameter and the inner diameter of the piston ring are in the range of φ1250-φ1600mm, the thickness is in the range of 30-50mm, the outer circle size tolerance is f7(-0.110--0.235)mm, the inner hole size tolerance is H8(+0.195-0)mm, and the thickness size tolerance is f8(-0.025--0.064)mm. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 End face, inner hole machining clamping schematic diagram;

[0025] Figure 2 Tool flange structure schematic diagram;

[0026] Figure 3 Press block perspective view;

[0027] Figure 4 Piston ring front view;

[0028] Figure 5 Piston ring outer circle machining clamping schematic diagram;

[0029] Figure 6 Tool flange with boss schematic diagram.

[0030] Wherein, 1, tool flange; 1-1, groove; 1-2, upper end face; 1-3, outer ring threaded hole; 1-4, inner ring threaded hole; 1-5, flange plane; 1-6, boss; 2, press block; 2-1, press block end face; 2-2, waist-shaped hole; 3, locking bolt; 4, piston ring; 4-1, inner hole face; 4-2, outer circle face; 4-3, sealing groove; 4-4, lower end face; 4-5, upper end face. DETAILED DESCRIPTION

[0031] The application will be further described below in combination with the drawings.

[0032] The tooling of the application comprises a tool flange 1, a press block 2 and a locking bolt 3, wherein the tool flange 1 is a disc, the upper end face of the tool flange is provided with a plurality of grooves 1-1 (8 in this embodiment) on the circumference, and a plurality of threaded holes 1-3, 1-4 (8 in this embodiment, respectively) are uniformly distributed on the inner and outer rings; the press block 2 has a waist-shaped hole 2-2.

[0033] Process:

[0034] I, the tool flange 1 is placed on the numerical control vertical lathe chuck, with groove 1-1 upper end surface 1-2 upward, using numerical control vertical lathe chuck jaw clamping. Finish turning tool flange 1 upper end surface 1-2, ensure tool flange 1 upper end surface flatness ≤0.02mm. The piston ring 4 is placed on the tool flange 1 plane, the lower end surface 4-4 of the piston ring 4 is upward, the eight pressing blocks 2 are placed uniformly, the end surface 2-1 of the pressing block 2 is in contact with the outer cylindrical surface 4-2 of the piston ring 4, the waist type hole 2-2 is aligned with the outer circle threaded hole 1-3 of the tool flange 1, and the piston ring 4 is fixed to the tool flange 1 by using the locking bolt 3 and the pressing block 2. Finish turning the lower end surface 4-4 of the piston ring 4, leaving a single side 0.4-0.5mm finishing allowance, and detecting with a dial gauge to ensure that the end surface runout is ≤0.02mm; When measuring the thickness size, measure from the groove 1-1 part of the tool flange 1;

[0035] II, loosen the pressing block 2, turn over the piston ring 4, the upper end surface 4-5 of the piston ring 4 is upward, the lower end surface 4-4 of the piston ring 4 is in contact with the upper end surface 1-2 of the tool flange 1, then rotate the piston ring 4 a few times, grind the end surface to improve the contact degree, the end surface 2-1 of the pressing block is in contact with the outer cylindrical surface 4-2 of the piston ring, the waist type hole 2-2 is aligned with the outer circle threaded hole 1-3 of the tool flange 1, and the inner hole surface 4-1 of the piston ring 4 is used as a reference, and the outer cylindrical surface 4-2 allowance is rechecked. The piston ring 4 is fixed to the tool flange 1 by using the locking bolt 3 and the pressing block 2, the upper end surface 4-5 of the piston ring is finish turned, leaving a single side 0.4-0.5mm finishing allowance, and detecting with a dial gauge to ensure that the end surface runout is ≤0.02mm, and when measuring the thickness size, measure from the groove 1-1 part of the tool flange 1;

[0036] III, finish turning the inner hole surface 4-1 of the piston ring 4, leaving a single side 0.4-0.5mm allowance, ensuring that the inner hole surface of the piston ring 4 is ≤0.03mm, and recording the actual measured size D1 of the inner hole.

[0037] IV. Remove the piston ring 4, the flange 1 end face 1-2, the formation of the center boss 1-6 (boss 1-6 and flange 1 concentric) and flange plane 1-5, boss 1-6 outer diameter D2, height 5-6 mm. According to the piston ring 4 bore size D1 measured size D2, ensure that the piston ring 4 outer diameter boss 1-6, 0.02-0.03 mm interference. The piston ring 4 is fixed to the flange 1 boss 1-6, the piston ring 4 inner hole face 4-1 and flange boss 1-6 outer circle, using a rubber hammer gently knock the piston ring 4 end face 4-5, with a plug gauge check the piston ring 4 end face 4-4 and flange plane 1-5 gap, ensure 0.03 mm not into. The eight blocks 2 are placed uniformly, the block end face 2-1 and the piston ring 4 inner circle 4-1 contact, the waist hole 3-2 and the flange 1 inner circle thread hole 1-3 alignment, using locking bolt 3 and block to fix the piston ring 4 on the flange. Finish turning the piston ring 4 outer circle 4-2 and the sealing groove 4-3, the outer circle leaves both sides 0.1 mm polishing allowance, polishing the piston ring 4 outer circle 4-2 to the requirements. The piston ring 4 is taken out from the flange 1.

[0038] V) after the natural aging ≥5 days, re-measure the piston ring 4 outer circle 4-2 size, meet the requirements, turning flange 1 boss 1-6 outer circle, ensure that the boss 1-6 outer circle diameter D3 than the piston ring inner hole face 4-1 small side ≥30 mm, to avoid the boss 1-6 influence the subsequent piston ring 4 inner hole face 4-1 processing. The piston ring 4 is placed on the flange 1, with the piston ring 4 outer circle alignment, ensure that the outer circle runout ≤0.03 mm requirements, the eight blocks 2 are placed uniformly, the block end face 2-1 and the piston ring outer circle 4-2 contact, the waist hole 3-2 and the flange 1 thread hole 1-3 alignment, using fastening bolt 3 and block to fix the piston ring 4 on the flange 1. Finish turning the piston ring upper end face 4-5, using the dial gauge to detect the end face runout ≤0.02 mm requirements; turn over, the piston ring 4 lower end face 4-4 upward, the piston ring 4 upper end face and the flange 1 upper end face flat after a few turn the piston ring 4, grinding end face to improve the degree of fit, using a plug gauge check the piston ring end face and the flange 1 upper end face gap, ensure 0.03 mm not into. The block end face 2-1 and the piston ring outer circle 4-2 contact, the waist hole 2-2 and the flange 1 outer circle thread hole 1-3 alignment, with the piston ring outer circle 4-2 as a reference, using fastening bolt 3 and block 2 to fix the piston ring 4 on the flange 1, finish turning the piston ring 4 lower end face, using the dial gauge to detect the end face runout ≤0.02 mm, when measuring the thickness size, from the flange 1 groove 1-1 part. After meeting the thickness size requirements, finish turning the piston ring 4 inner hole face 4-1, leaving both sides 0.1 mm polishing allowance, polishing the inner hole face 4-1 to the design requirements.

[0039] The method can batch produce high-precision thin-wall nickel-copper alloy piston ring forgings with high processing efficiency and good precision; eight piston ring forgings are produced by the method, and detection shows that all indexes meet design requirements: the outer diameter and inner diameter of the piston ring ranges from 1250 to 1600 mm, the thickness ranges from 30 to 50 mm, the outer circle size tolerance is f7 (-0.110 to -0.235) mm, the inner hole size tolerance is H8 (+0.195 to 0) mm, the thickness size tolerance is f8 (-0.025 to -0.064) mm, and the product processing qualified rate is 100%. Before the method is used, it takes 15 days to finish machining one piston ring, and after machining, local size is out of tolerance. After the method is used, the finish machining time is reduced to 7 days, and after machining, no size is out of tolerance.

Claims

1. A method for finish machining of a large-diameter high-precision thin-walled nickel-copper alloy piston ring forging, characterized in that, The tool flange is provided with a plurality of uniformly distributed threaded holes in the inner and outer circles of the upper end face; It comprises the following steps: I. Place the tool flange on the numerical control vertical lathe chuck, with the top surface facing up, clamp it with the numerical control vertical lathe chuck jaws, place the piston ring on the upper end face of the tool flange, with either end face of the piston ring facing up, place a plurality of pressing blocks evenly on the tool flange outside the piston ring, with the end face of the pressing block in contact with the outer cylindrical surface of the piston ring, align the waist-shaped hole on the pressing block with the threaded hole in the outer circle of the tool flange, use locking bolts to pass through the waist-shaped hole on the pressing block and fix the tool flange, thereby fixing the piston ring to the tool flange; finish machining either end face of the piston ring, leaving a single-sided 0.4-0.5mm finishing allowance, use a dial indicator to ensure that the end face runout is ≤0.02mm; II. Turn over the piston ring, with the other end face facing up, make the either end face of the piston ring fit the upper end face of the tool flange, repeat step I, finish machining the other end face of the piston ring, leaving a single-sided 0.4-0.5mm finishing allowance, use a dial indicator to ensure that the end face runout is ≤0.02mm; III. Finish machining the inner hole surface of the piston ring, leaving a single-sided 0.4-0.5mm allowance, ensuring that the inner hole surface of the piston ring is ≤0.03mm in cylindricity, record the actual measured size D1 of the inner hole; IV. Remove the piston ring from the tool flange, turn the boss on the upper end face of the tool flange, the outer diameter of the boss is D2, the height is 5-6mm, according to the actual measured size D1 of the inner hole of the piston ring, turn the outer diameter of the boss, ensuring that the interference is 0.02-0.03mm; fix and install the piston ring to the tool flange, with the inner hole surface of the piston ring cooperating with the outer diameter of the boss on the tool flange; place a plurality of pressing blocks evenly, with the end face of the pressing block in contact with the inner cylindrical surface of the piston ring, align the waist-shaped hole with the threaded hole in the inner circle of the tool flange, use locking bolts to pass through the waist-shaped hole on the pressing block and fix the tool flange, thereby fixing the piston ring to the tool flange; finish machining the outer cylindrical surface and the sealing groove of the piston ring, leaving a double-sided 0.1mm polishing allowance on the outer cylindrical surface, polish the outer cylindrical surface of the piston ring to the design requirements; V. Remove the piston ring, turn the outer diameter of the boss on the tool flange, ensuring that the outer diameter D3 of the boss after turning is smaller than the inner hole surface of the piston ring by a single side ≥30mm; place the piston ring on the tool flange, align it with the outer cylindrical surface, ensuring that the outer cylindrical runout is ≤0.03mm, repeat steps I-III, in turn finish machining either end face, the other end face, and the inner hole surface of the piston ring to the design requirements.

2. The finish machining method of a large-diameter high-precision thin-wall nickel-copper alloy piston ring forging as set forth in claim 1, characterized by, In step II, after turning over the piston ring, manually rotate the piston ring for end face grinding after making either end face of the piston ring fit the upper end face of the tool flange.

3. The method of claim 1, wherein the high-precision thin-wall nickel-copper alloy piston ring forging is a large-diameter high-precision thin-wall nickel-copper alloy piston ring forging. In step IV, after fixing and installing the piston ring to the tool flange, use a rubber hammer to gently knock the upper end face of the piston ring, use a feeler gauge to check the gap between the lower end face of the piston ring and the upper end face of the tool flange, ensuring that it is not more than 0.03mm.

4. The method of claim 1, wherein the high-precision thin-wall nickel-copper alloy piston ring forging is a large-diameter high-precision thin-wall nickel-copper alloy piston ring forging. In step V, after removing the piston ring from the tool flange, first place it naturally for aging ≥5 days.

5. The method of finish machining a large diameter high-precision thin-walled nickel-copper alloy piston ring forging according to any one of claims 1 to 4, characterized in that, The upper end face of the tool flange is uniformly provided with a plurality of grooves in the circumferential direction, the front end of the groove protrudes beyond the position of the upper end face of the tool flange corresponding to the outer cylindrical surface of the piston ring.

6. The method of claim 5, wherein the high-precision thin-wall nickel-copper alloy piston ring forging is a large-diameter high-precision thin-wall nickel-copper alloy piston ring forging. Measure the thickness of the piston ring by using the groove of the tool flange and the outside diameter micrometer with a range of 25-50mm.

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